Big myth and big falsehood.  70/80 GHz links have such a narrow beamwidth that interception is virtually impossible.  And, while some wireless can be easily intercepted at low frequencies even that doesn’t make it a particular security risk.  Consider that cables can be just as easily identified in conduits and junction boxes and that data can be stripped in either case.

The key again is planning and using tools to protect data.  There are many arguments on this topic but if the need for security is high then information that is being transmitted should be encrypted/protected at the source and during transmission.  The good news here is that there is an entire industry that deals with security and data protection and GigaBeam is engaged with a number of the players in this space.